1. The Field of the Invention
This invention relates to memory devices and, more particularly, to novel systems and methods for directing a light beam to read and write from a medium for storing information.
2. The Background Art
Memory devices have existed to support computers since computation was invented. Memory devices for modern computer systems meet physical limitations controlling the ability to write data, read data, and to reliably store data. In more recent years, electromagnetic media have been augmented, sometimes replaced, by optical media. For example compact disk read only memory (CD ROM) has become a major distribution medium for software, data, reference materials, images, art works, music, and the like. As a practical manner, the total available number of bits that may be stored in a CD ROM or any optical or electromagnetic memory device is limited by its "resolution." Various physical and electrical factors contribute to limitations on resolution.
An ability to direct a writing device, direct a reading device, prevent interaction between bits, and the like have limited density of media recording data. Moreover, fundamental mechanical limitations exist for reading heads and writing heads in memory devices. The quality of signal processing and available limitations on speed have together combined to produce the information storage technologies used in the prior art.
The density of data on an actual storage medium is important. Also, the overall density of data for the entire storage medium and its supporting infrastructure may be very significant. Memory density may be thought of as the inverse of resolution. For example, the number of bits that may be stored in any medium of a particular size, such as an area or a volume, may characterize a storage density as that number of bits per that particular volume, area, or other resource measurement.
In modern memory systems, particularly non-volatile ones, such as hard drives, floppy diskettes, Bernoulli drives, electro-optical disks, CD ROM's, and the like, have relied on certain moving mechanical parts. Typically, a storage medium is configured in a circular format to be rotated. Meanwhile, a mechanical head may traverse radially over the rotating medium. Thus, electronic control of starting and stopping of reading may selectively read or write along an arcuate path over a medium. The rotating speed of a medium, coupled with the speed of the electronic switching to begin or end reading or writing, and the mechanical accelerations available for moving the head radially have traditionally controlled the speed, resolution, and densities of memory devices.
The memory devices available in the prior art are positioned in many locations with respect to the actual processors using or creating data stored therein. For example, a computer may have a level I cache. The level I cache is typically located immediately on the computer chip that holds the processor itself. Other caches may be located more remotely. For example, other caches may be located across the computer bus on a motherboard or other highly integrated portion of a computer close to the central processing unit (CPU).
Random access memory may be located even more remotely from the CPU than is the cache. Random access memory may be located in a chip on the mother board of a computer and connected by the main computer bus thereon. Hard disks, floppy diskette, and the like, along with optical CD ROM readers, and CD ROM writers, may be connected to a computer as peripheral devices.
Much of computer architecture is driven by the sizes of components. Moreover, the speed of access to memory devices is often critical. Thus, a CPU does not access the hard drive for data or other data structures (e.g. applications or other executables) if the required data structures may be stored to be accessible in the random access memory (RAM). Similarly, an executable line of code that may be stored in a cache will be found there first, if available. Thus, a CPU seeks to find data structures required for operation in the closest, fastest, available location. Architectures of all operating systems are crafted to manage information in the caches, RAM, and storage (e.g. ROM, CD ROM, hard drive, floppy drive, etc.).
Thus, computer speed is limited by the proximity and availability of data or data structures, whether executables or simply operational data. Making more memory available in a smaller envelope (total size) permits a memory device to be located closer to the CPU in terms of access speed. Minimizing mechanical parts speeds the accessability to data in a memory device.
Not only do moving mechanical parts take relatively large space with respect to a CPU, but they generate heat and shock loads that may harm integrated compounds. Also, mechanical devices use substantial electrical energy. Large users of electrical energy may affect the voltages, inductance and, generally, the conditioning of available voltages and currents used in electronic circuits. Thus, mechanical devices are typically located remotely from less robust, electronic components operating at more stable voltages and lower currents.
Mechanical parts wear. Tolerances change. Time, temperature, wear, and abuse change their physical operation. Newton's second law of motion still limits their theoretical, maximum, response speed.
Thus, what are needed are increased storage densities for memory, and a reduction of mechanical parts. What is needed is increased memory resolution and density at increased operational speed. Preferably, memory is needed that can be available in a solid state. Storage of data in an envelope of reduced size, at an access speed corresponding to the speeds of electrons and light rather than mechanical responses, may provide improved memory support for increasingly large applications and other executables.
In addition, laser technology and other electromagnetic radiation beam technologies are being applied in varied ways. In general, directing a beam, such as a laser beam, more rapidly, with higher resolution, may be used in applications as diverse as surgery, holographic displays and readers, oscilloscopes, switches, and logical devices. Thus, any available use of lasers, electromagnetic radiation, light, and the like may benefit from higher speed in direction, and increased resolution thereof. High speed and precision pointing are required.